straight blades

Fiddleback

Fiddleback

Knifemaker
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Knifemaker / Craftsman / Service Provider
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I forged a blade last weekend. Afterward I normalized it. Yesterday I took it out of the vermiculite and its not quite straight. I could probably grind out this minute bit of curve, but I'd rather heat it up and straighten it out. Do you guys have any tricks/hints on this process. I don't want to keep correcting one way then another. Should I just grind it out?
 
Andy, you say you took it out of the vermiculite. That is typically the annealing stage - hot blade into vermiculite for a lamellar anneal. In other words, the softening of the steel prior to working.

Normalizing is heating the blade to critical and cooling it in still air to room temperature.

Here is the way I would do it. Heat the blade and gently straighten it. Bring it back up to critical and normalize. You can anneal again later once the blade is straight.

I have found over the years that if a blade is crooked after normalizing or annealing that it will often warp during hardening. I have found the reverse to also be true; blades that remain straight after repeated thermal cycling rarely warp during the quench. Additional normalizing almost always solves the warping problem.

Keep in mind that if you do get some warpage during the quench you can straighten the blade until it falls below ~400 F.
 
Lemme restate. After working the steel from rod to flat blank, and pounding an edge into it, I heated to critical and allowed it to air cool twice. Then I annealed (heated and into vermiculite).

The "warp" didn't happen during these phases. It was "cupped" from my hammering. My question is whether there is a trick to hammering a blade straight, or even checking a HOT blade for straight without burning my nose off.
 
Mace Vitale showed me a method using a piece of soapstone... run the soapstone up and down the edge (or the spine, whichever you're trying to make straight), that way it'll give you a clear, bright view (when sighting down the edge with a dark background) of what needs to be straightened and where.

Was that a clear explanation, or did that not make any sense at all?
 
Im not very good at my hammer work yet, and so when I forge a blade it's bent all over the place.

As I get closer to being done with the hot hammering, i start to straighten the blade. I will get the blade red hot and then just stick it in my bench vise and work it up and down in the jaws of the vise untill I get it all straight.

The bench vise also holds the blade steady while I fix any twists in the blade edge too.
Sometimes I even let the blade cool in the jaws so I know it's right.

I had a few blades bend in the kitchen oven when tempering, so now I also clamp them in a drillpress vise to hold straight while temperiing
 
Fiddleback said:
Lemme restate. After working the steel from rod to flat blank, and pounding an edge into it, I heated to critical and allowed it to air cool twice. Then I annealed (heated and into vermiculite).

The "warp" didn't happen during these phases. It was "cupped" from my hammering. My question is whether there is a trick to hammering a blade straight, or even checking a HOT blade for straight without burning my nose off.
Click to expand...

Is it a warp or is there a upward curve in the spine? If its the spine its a pretty simple fix to straighten out. Put the blade spine down on the anvil after its good and hot and hit it with a 2X4 until the spine is flat on the anvil. You'll have to straighten the rest of the blade out afterwards and don't do a bunch of hammering on the bevel or you'll be back where you just started.
 
Yeah, there are a few tricks you can try.

first, to straighten your current piece, get a piece of firewood, a 2x4, or an old wood bat, any kind of wooden club. heat the blade to a cherry red(yes, I know colors are subjective, but in this case you don't want the steel too hot) place the blade edge flat on the anvil and lay your hammer on it to pull out some of the heat where the blade is thinnest, this should only take a few seconds. then lay the blade spine on the anvil, edge up, and whack it with the club. if you hit the blade squarely, there should be little to no warping on the edge. if you were to hit the edge with a hammer, you would probably warp or dent the edge. Using a softer material as a hammer can convince a piece of steel to bend without disfiguring an edge. I generally call my club a Thwak'em stick, after Battlelords of the 23rd century. :)

to help out next time, forge your blade into the general shape that you want, then before you start forging the edge, put a prebend in it. hold the tang of the blade about 1- 1 1/2" above the anvil, with the piont of the blade on the anvil, the soon to be edge up, and thwak it once or twice. then when you forge out the edge, the spine should straighten out. It takes a little practice to find out just how much bend you want in the blade.

Good luck
Ken
 
WOW!! Thanks for the advice fellas. The blade was just hammered a little poorly. I heated it and carefully hammered it straight, and got to grinding. Then I normalized it, and after it cooled stuck it back in the forge for heat treating. But, I melted off the tip, so now its a big hunk of terd.

Live and learn. That damn forge is HOT. Kinda bummed, but you gotta screw em up to learn the limits right?????:o
 
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